[37] Guanosine triphosphate-8-formylhydrolase

Biosynthesis of pyrrolopyrimidines

“…GCH I catalyzes the conversion of GTP to 7,8-dihydroneopterin triphosphate (H 2 NTP), in a reaction that leads to loss of carbon-8, retention of carbon-2, and incorporation of the ribose carbons to form a new ring system. Consistent with the radiotracer experiments, dialyzed cell lysates from S. rimosus , which produces both sangivamycin and toyocamycin, contained GCH I activity [45,46]. While the lysate affected the loss of radioactivity from [8- 14 C]-GTP as formic acid, similar activity was not observed toward [8- 14 C]-ATP or ITP.…”

Biosynthesis of 7-Deazaguanosine-Modified tRNA Nucleosides: a New Role for GTP Cyclohydrolase I

“…In Salmonella enterica serovar Typhimurium, incorporation into Q was observed with [2][3][4][5][6][7][8][9][10][11][12][13][14] C]guanine, but not with [8][9][10][11][12][13][14] C]guanine, suggesting a loss of carbon-8 in a process analogous to that observed in the early step of pteridines and folic acid (25). In Streptomyces, a nonconstitutive GCYH was implicated in toyocamycin biosynthesis (10,11). It was recently shown that a GCYH-I gene was indeed involved in deazapurine biosynthesis (31).…”

13C‐NMR evidence for the biosynthetic incorporation of acetate into minimycin and compounds related to krebs cycle

“…The extensive recycling through the Krebs cycle and the shunt pathways would not result in randomization of the label seen in the case of [2-13 C]acetate [2,3]. Scheme 2 illustrates that the C-C coupling pattern of the Krebs cycle member acids remains unchanged after multiple recycling.…”

“…However, its application to the biosynthesis of the compounds derived from the Krebs cycle has been limited because of the high isotope dilution and extensive randomization through the cycle. To our knowledge, the maleimide ring of showdomycin [2] and the a-aminoadipoyl group of penicillin Nand cephalosporin C [3] are the only examples of this class of compounds utilizing [1-or 2- 13 C]acetate for their biosynthetic study. We considered that this difficulty may be overcome by utilizing doubly-labeled [1 ,2-13 C]acetate from the following reasons.…”